Apparatus for cleaning lines on a playing surface and associated methods, handle enhancements

ABSTRACT

An apparatus and method for clearing a playing surface are provided. The apparatus preferably includes a chassis or frame, a sensor connected to the chassis to sense a location of a line on a playing surface that needs to be cleaned, a drive connected to the chassis to drive the chassis in a selected direction of travel, and a handle to facilitate handling by a user. The apparatus also preferably includes a controller connected to the chassis, in communication with the drive, and responsive to the sensor to control the drive to thereby direct the chassis to move along the line that needs to be cleaned in the selected direction of travel and a cleaning device connected to the chassis to clean the line with the chassis is being driven along the line. Associated software is provided as well.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior nonprovisionalpatent application U.S. Ser. No. 11/810,418, filed Jun. 5, 2007, andtitled “Methods For Cleaning Lines On A Game Playing Surface”, which isa continuation-in-part of prior nonprovisional patent application U.S.Ser. No. 10/977,786, filed Oct. 29, 2004, and titled “Apparatus ForCleaning Lines On A Playing Surface And Associated Methods,Enhancements”, which is a continuation-in-part of prior nonprovisionalpatent application U.S. Ser. No. 10/226,978, filed Aug. 23, 2002, andtitled “Apparatus For Cleaning Lines On A Playing Surface And AssociatedMethods”, which claims the benefit of prior provisional patentapplication U.S. Ser. No. 60/314,933, filed Aug. 24, 2001, and titled“Automatic Propulsion, Navigation and Control of Cleaning Device forTennis Court Lines”, which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the surface maintenance and treatmentindustries in general and, in particular, to an apparatus and methodsfor cleaning lines on a playing surface.

2. Description of the Related Art

A tennis court is a flat surface defined by multiple boundary lines,namely, sidelines, baselines, service lines, and center lines. Thedouble's sidelines, single's sidelines and baselines define the backcourts. The single's sidelines and service lines define the servicecourts. The center lines divide the service courts. For a hard court,the above-mentioned boundary lines are typically drawn beforehand on asheet of plastic pasted over a concrete base. For a clay or lawn court,the above-mentioned boundary lines are typically prepared by fixingwhite tape on a playing surface via tacks.

In general, a clay-surface tennis court or clay court requires dailymaintenance in the form of smoothing and watering. The smoothing processis typically performed by dragging a broom or brush across the entiresurface of the clay court for smoothing out the loose material on thesurface of the clay court. After the smoothing process, the boundarylines on the clay court are usually covered with clay dust. As such, theboundary lines must be cleared of the clay dust before watering and/orbefore any serious play can be conducted on the clay court. Also, afterseveral games have been played on the clay court, the boundary lines mayagain be covered by clay dust that necessitates cleaning. Commonly, thecleaning is performed by a person walking a roller brush over all thelines of the clay court, which is very laborious and time-consuming, notto mention tiresome. An example of such a roller brush can be seen inU.S. Pat. No. 4,958,400 by Sugita titled “Line Cleaning Apparatus.”Consequently, it is desirable to provide an apparatus for enhancing thecleaning of boundary lines on a playing surface such as a tennis court.

SUMMARY OF THE INVENTION

The present invention advantageously provides an apparatus and methodsfor enhancing the cleaning of boundary lines on a playing surface whichsubstantially reduces or eliminates the manual labor involved in caringfor the playing surface. The present invention also advantageouslyprovides a cleaning apparatus and methods that reduce the time involvedin caring for a playing surface. The present invention additionallyadvantageously provides a cleaning apparatus and methods that sense thepresence of a boundary line that needs to be cleaned and directs thecleaning of the line without the need for any substantial manual labor.

The present invention still also advantageously provides a cleaningapparatus and methods having familiarity or dimensions of a playingsurface, such as a clay-surface tennis court, stored in memory, anddirects the cleaning of the boundary lines of the tennis court bysensing the presence of or a location of the boundary lines.

More particularly, the present invention provides an apparatus forcleaning boundary lines on a playing surface which has a cleaningdevice, a drive positioned to drive the cleaning device along at leastone boundary line of a playing surface, and a controller incommunication with the drive and the cleaning device to selectivelycontrol the driving of the cleaning device to clean the at least oneboundary line on the playing surface when the drive is driving thecleaning device along the at least one boundary line.

The present invention also provides an apparatus for cleaning lines on agame playing surface which has a chassis, sensing means connected to thechassis for sensing a location of a line associated with a game playingsurface that needs to be cleaned, driving means connected to the chassisfor driving the chassis in a selected direction of travel, controllingmeans connected to the chassis, in communication with the driving means,and responsive to the sensing means for controlling the driving means tothereby direct the chassis to be driven along the line that needs to becleaned in the selected direction of travel, a cleaning device connectedto the chassis to clean the line when the chassis is being driven alongthe line, and a handle to facilitate handling of the apparatus by auser.

The present invention also provides methods of cleaning boundary lineson a playing surface. A method for cleaning boundary lines on a playingsurface preferably includes positioning a cleaning device on or near agame playing surface, directing a cleaning device to move along boundarylines on a playing surface responsive to a set of programmed directions,and cleaning the boundary lines when the cleaning device is moving alongthe boundary lines.

Another method for cleaning boundary lines on a game playing surfacepreferably includes directing a cleaning device to move along boundarylines on a game playing surface responsive to a set of programmeddirections, and selectively positioning a cleaning tool on a boundaryline to clean the boundary line as the cleaning device is moving overthe boundary line.

Yet another method for cleaning boundary lines on a game playingsurface, which has a first playing surface and a second playing surfaceseparated from each other by a net connected between a plurality ofposts, preferably includes directing a cleaning device to move alongboundary lines on the first playing surface responsive to a set ofprogrammed directions, cleaning the boundary lines on the first playingsurface as the cleaning device is moving over the boundary lines on thefirst playing surface, directing the cleaning device to move around oneof the net posts to position the cleaning device on the second playingsurface, and cleaning the boundary lines on the second playing surfaceas the cleaning device is moving over the boundary lines on the secondplaying surface.

The present invention further provides a computer program productresiding on a computer usable medium for directing a cleaning device toclean at least one line on a surface. A computer program productpreferably includes program code means for directing a cleaning deviceto move along at least one line of a surface and program code means forcleaning the at least one line on the surface when the cleaning deviceis moving along the at least one line.

Another computer program product for cleaning boundary lines on a gameplaying surface is provided according to the present invention. Thecomputer program product includes program code means for directing acleaning device to move along boundary lines on a game playing surfaceresponsive to a set of programmed directions and program code means forselectively positioning a cleaning tool on a boundary line to clean theboundary line as the cleaning device is moving over the boundary line.

Another computer program product for cleaning boundary lines on a gameplaying surface, which includes a first playing surface and a secondplaying surface separated from each other by a net connected between aplurality of net posts, is also provided. The computer program productincludes program code means for directing a cleaning device to movealong boundary lines on the first playing surface responsive to a set ofprogrammed directions, program code means for cleaning the boundarylines on the first playing surface as the cleaning device is moving overthe boundary lines on the first playing surface, program code means fordirecting the cleaning device to move around one of the net posts toposition the cleaning device on the second playing surface, and programcode means for cleaning the boundary lines on the second playing surfaceas the cleaning device is moving over the boundary lines on the secondplaying surface.

Accordingly, the present invention advantageously provides a cleaningapparatus and methods which selectively operate a cleaning device whenthe location or presence of a boundary line is sensed or when thecleaning apparatus determines that a boundary line needs to be cleaned.The present invention further advantageously provides software toenhance the cleaning of a surface such as boundary lines on a tenniscourt or other selected surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the features and advantages of the present invention having beenstated, others will become apparent as the description proceeds whentaken in conjunction with the accompanying drawings, in which:

FIG. 1 is an environmental view of a cleaning apparatus being used forcleaning lines on the playing surface of a tennis court according to anembodiment of the present invention;

FIG. 2 is a perspective view of a cleaning apparatus according to anembodiment of FIG. 1 of the present invention;

FIG. 3 is a perspective view of a cleaning apparatus according toanother embodiment of the present invention;

FIG. 4 is a perspective view of a cleaning apparatus according to yetanother embodiment of the present invention;

FIG. 5 is a bottom plan view of a cleaning apparatus according to theembodiment of FIG. 3 of the present invention;

FIG. 6 is a side elevational view of a cleaning apparatus according tothe embodiment of FIG. 3 of the present invention;

FIG. 7 is a top plan view of a cleaning apparatus according to theembodiment of FIG. 3 of the present invention;

FIG. 8 is a rear elevational view of a cleaning apparatus according tothe embodiment of FIG. 3 of the present invention;

FIG. 9 is a block diagram of a cleaning apparatus according to anembodiment of the present invention;

FIG. 10 is a schematic diagram of a line-sensing module within acleaning apparatus according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of a propulsion module within thecleaning apparatus according to an embodiment of the present invention;

FIG. 12 is a flowchart illustrating operation of a cleaning apparatusand associated software and methods according to an embodiment of thepresent invention;

FIG. 13 is a top plan view of a cleaning route on a tennis court, inaccordance with an embodiment of the present invention;

FIG. 14 is a schematic view of a route for a cleaning apparatus totravel around a net post of a tennis court according to the presentinvention;

FIG. 15 is a flow chart of operation of a cleaning apparatus fortraveling around a net post of a tennis court according to the presentinvention; and

FIG. 16 is a flowchart illustrating operation of a cleaning apparatusand associated software and methods according to an embodiment of thepresent invention.

DETAILED DESCRIPTION

The present invention will now be described more fully with reference tothe accompanying drawings. The present invention, however, may beembodied in many different forms and should not be construed as limitedto the illustrated embodiments set forth herein. Rather, suchembodiments are provided so that the present disclosure will be thoroughand complete, and will fully convey the scope of the present inventionto those skilled in the art. Like numbers refer to like elementsthroughout, incremental hundred numbers, if used, indicate similarelements in alternative embodiments.

FIG. 1 illustrates a cleaning apparatus 30 cleaning boundary lines on asurface such as a tennis court 20 in accordance with an embodiment ofthe present invention. As shown, a tennis court 20 is a flat surfacedefined by single's sidelines 21 a-21 b, double's sidelines 22 a-22 b,baselines 23 a-23 b, service lines 24 a-24 b, and center lines 25 a-25b. The single's sidelines 21 a-21 b, the double's sidelines 22 a-22 band the baselines 23 a-23 b define the back courts. The single'ssidelines 21 a-21 b and the service lines 24 a-24 b define the servicecourts. The center lines 25 a-25 b divide the service courts. Thebaselines 23 a and 23 b include center marks 26 a and 26 b,respectively. The size of a standard single's court is defined as 27feet by 78 feet, and the size of a standard double's court is defined as36 feet by 78 feet. The size of a standard service court is defined as27 feet by 42 feet. As depicted in FIG. 1, a cleaning apparatus 30 forcleaning boundary lines on the tennis court 20 is shown to be cleaningthe double's sideline 22 b. Preferably, the tennis court 20 has a clayor fast dry surface, or any of the other variety of clay-like surfacessometimes referred to as “clay” or “soft,” including those that may bereferred to by their trademarked or brand names such as Har-Tru orFast-Dri, and require routine maintenance that generally involvessmoothing and sweeping the surface and brushing the lines.

FIGS. 2-9 illustrate a cleaning apparatus 30, in accordance with threedifferent embodiments of the present invention. As shown, the cleaningapparatus 30, 130, 230 includes a main frame or chassis 35, 135, 235sensing means, such as provided by a line-sensing module 31, 131, 231,connected to the chassis 35, 135, 235 for sensing a location or presenceof a line associated with a surface or a game playing surface that needsto be cleaned, driving means, such as provided by a propulsion or drivemodule 33, connected to the chassis 35, 135, 235 for driving the chassisin a selected direction of travel, controlling means, such as providedby a navigation and control module 32, connected to the chassis 35, 135,235, in communication with the driving means, and responsive to thesensing means for controlling the driving means to thereby direct thechassis to be driven along the line that needs to be cleaned in theselected direction of travel, and a cleaning device 34, 134, 234connected to the chassis 35, 135, 235 to clean the line when the chassis35, 135, 235 is being driven along the line, and a handle 39, 139, 239to facilitate handling of the apparatus by a user. The line-sensingmodule 31 senses various landmarks (such as lines of specific lengths,net posts, line boundaries) on the tennis court 20 via a sensing devicesuch as a sonar, a radio frequency sensor, a transducer, a camera, acharge coupled device, photo-optical sensors, radar, a laser or bycontact. The design, position and orientation of the line-sensing module31 preferably allow landmarks that are far away from or in closeproximity with the cleaning apparatus 30, 130, 230 to be sensed. Thesense data information obtained by the line-sensing module 31 iscommunicated to the navigation and control module 32 for the purpose ofnavigating the movement of the cleaning apparatus 30, 130, 230. Afterreceiving the sense data information from the line-sensing module 31,the navigation and control module 32 determines the position of thecleaning apparatus 30 in relation to the detected landmark on the tenniscourt 20, and then controls the propulsion module or drive 33 to move toand along a specific boundary line on the tennis court 20. The sensingdevice is preferably positioned at an elevation higher than the gameplaying surface and is preferably oriented to capture an image or datain a direction transverse to the game playing surface. The propulsion ordrive module 33 includes an energy supply such as a battery or a fuelcell and an appropriate motor (not shown) for driving wheels, treads,rollers, or other devices to assist travel along a surface. In thepresent embodiment, movements of the cleaning apparatus 30 are assistedby a pair of drive wheels 36 and a swivel wheel 37. The cleaning device34 is also activated and deactivated as appropriate to clean a boundaryline on the tennis court 20 when the cleaning apparatus 30 is movingalong the boundary line. The cleaning device 34 can be a brush, abristle, an air blower, or other cleaning or surface treatment tool asunderstood by those skilled in the art. The navigation and controlmodule 32 can activate the cleaning device 34 for cleaning when thecleaning device 34 is positioned over a portion of the boundary linethat needs to be cleaned, or can deactivate the cleaning device 34otherwise. The exercise of such control over the cleaning device 34 canconserve energy and can minimize the disturbance to the court surfaceoutside of boundary lines.

FIG. 10 illustrates a line-sensing module 31, in accordance with anembodiment of the present invention. As shown, line-sensing module 31includes a plurality of or an array of emitters such as infrared or IRemitters 41 and a sensing device 42, e.g., an optical sensing device orcamera, having a sensor 43 and at least one lens 44 positioned to helpfocus light onto the sensor 43. Alternative, for example, the infraredemitters 41, can be light emitting diodes (LEDs) as understood by thoseskilled in the art. The sensing device 42 is positioned for viewing orsensing in a direction transverse to the court surface with its field ofview (FOV) centered at a point in the court area where a boundary line,such as a boundary line 45, is located when the cleaning apparatus 30 isbeing driven along (and optionally cleaning or treating) the boundaryline. As shown, for example, the FOV of the sensing device 42 can beperpendicular to the direction of the boundary line 45 and the FOV ofthe sensing device 42 can be slightly greater than the maximum width ofthe boundary line 45. The array of emitters 41 illuminates the courtarea for the camera 42. The purpose of the array of emitters 41 is toalways provide a sufficient illumination for the optical sensing device42, independent of the ambient lighting conditions in which the cleaningapparatus 30 are being operated. The sensing device also preferablyincludes a sensor interface positioned to serially shift out thecaptured image defined as a plurality of pixels as understood by thoseskilled in the art. A brightness level of each pixel, for example, canbe represented by or correspond to at least one voltage signal receivedover a controlled period of time as also understood by those skilled inthe art.

As illustrated in FIG. 2, preferably, the line-sensing module 31 isenclosed within a shroud 48. The shroud 48 can be an opaque cover, e.g.,formed of a plastic material, for protecting the sensing device 42 andother vision aspects from ambient light and/or other light impact.Although an embodiment of the sensing device 42 is optical in nature, itis understood by those skilled in the art that the sensing device 42 canbe implemented by acoustical sensing device, an electro-magnetic or amagnetic sensing device, radio frequency sensing device, a contactsensor and any other through-the-air or contact sensors.

As perhaps best shown in FIG. 10, an image of the boundary line 45 isdirected to the sensor 43 by the lens 44. The sensor 43 is an integratedcircuit containing a set of sensor elements positioned in a single line.The linear array of sensor elements captures the image received throughthe lens 44. The sensor 43 then serially shifts out the captured imagein analog form with the relative voltage of each pixel representing therelative illumination the pixel received over a controlled period oftime, i.e., the image integration time. Thus, the sensor 43 captures andsources an analog pixel stream that is in the form of a one-dimensional(linear) image. The line-sensing module 31 can also include amicrocontroller (or a microprocessor) 47 to control the integration timeof the sensor 43 and to control the shifting of the analog image comingout of the sensor 43. The microcontroller 47 converts the analog imageto a digital image for further processing.

The purpose of the line-sensing module 31 is to determine the lateraldisplacement of the cleaning apparatus 30 from a boundary line that isbeing followed. In order to perform such function, the cleaningapparatus 30 has to be able to process the image captured by theline-sensing module 31 and then determines if the boundary line ispresent, and the position or location of the boundary line in the FOV ofthe camera 42 if the boundary line is present. The characteristic of aboundary line that allows it to be distinguished from the court surfaceis the fact that the boundary line is more reflective of the irradiancereceived than the court surface. With the digital image, themicrocontroller 47 can analyze the information in the digital image viaa variety of image processing techniques, such as FOV attenuationadjustment as will be understood by those skilled in the art. Successiveimages are continuously captured and analyzed so that the presentlateral position of the cleaning apparatus 30 with respect to a boundaryline being followed can always be known.

If an area on the tennis court 20 that is being sensed is one over whichthe cleaning apparatus 30 has already passed, then the boundary lines inthat area should be free from loose materials. This fact supports morefidelity in determining whether a sensed area is on the boundary line ornot and in fact should allow the line-sensing module 31 to operatecorrectly even for boundary lines that are completely covered over whencleaning begins. For this reason, the line-sensing module 31 ispreferably positioned downstream from the cleaning device 34 (along thedirection of travel).

Given a known initial position and orientation on the tennis court 20,the cleaning apparatus 30 can determine its current position byfactoring in its change in position. The change in position can becalculated by odometric techniques that involve the continuousmeasurement of dynamic parameters such as wheel rotations andincorporate static parameters such as wheel diameter (or trackdimensions). The odometric technique of position determination, however,typically accumulates errors, and the errors need to be corrected whenthe cleaning apparatus 30 reaches various court landmarks (which can besensed based on knowledge of the fixed court geometry and knowledge ofthe approximate position of the cleaning apparatus 30) such as lineintersections at corners and tees (e.g., the intersection of thedouble's sideline 22 b and the baseline 23 a and the intersection of theservice line 24 a and the single's sideline 21 b, respectively).

At the ends of boundary lines and when traveling between boundary lines,it is sometimes necessary to steer the cleaning device 34 off anyboundary line. The navigation and control module 32 includes a linedeterminer (not shown) positioned to determine whether a boundary lineis present based on the captured image from the line-sensing module 31.This is accomplished in software, for example. The processing of theimages that are captured by the vision system results in a determinationof the presence or absence of the line in the camera FOV. Thisinformation is communicated to the navigation and control module 32.When the cleaning device 34 is not over the boundary line, thenavigation and control module 32 turns the cleaning device 34 off andretracts the cleaning device 34 to avoid disturbing the portions of thetennis court 20 that do not have a boundary line. The boundary lines ofthe portion of the tennis court 20 on one side of the net can betraversed and cleaned in a fixed order that is programmed into thenavigation and control module 32. When those boundary lines arecompleted, that side of the tennis court 20 is known to be finished. Thenavigation and control module 32 knows its position when it finishes oneside of the tennis court 20. By utilizing a position analyzer (notshown), the navigation and control module 32 knows the relative positionof any point across the net on the other side of the tennis court 20(based on the fixed standard court geometry). The position of theapparatus is known. The point at which cleaning is to begin on the otherside of the net is also known. The fixed standard court geometry thendefines the relative position of the two points. This information candefine a preprogrammed maneuver for moving from the final position onthe first half court to the desired starting position on the second halfcourt. This maneuver can be preprogrammed based on the relative positionof two points of interest, i.e., final point on the first half court andthe starting point on the second half court, respectively. Suchinformation can be used to navigate to any desired point on the otherside of the tennis court 20 based on the above-mentioned odometricpositioning techniques, and then by turning on the cleaning device 34 inthe proximity (the exact position may not be known because ofaccumulated error) of a boundary line to allow visible detection of theboundary line and thereby its accumulated position error. Such knownposition can be the same relative position as the position at which thecleaning apparatus 30 started cleaning on the first side of the tenniscourt 20. In the present embodiment, the line-cleaning algorithm used onone side of the tennis court 20 is simply repeated on the other side ofthe tennis court 20.

FIG. 11 illustrates a propulsion or drive module 33, in accordance withan embodiment of the present invention. As shown, the propulsion module33 includes two drive wheels 36 a-36 b and one or two pivoting, rotatingor swivel wheels or rollers 37. Each of the two drive wheels 36 a-36 bis driven by one of two differential battery powered drive motors 51a-51 b, respectively. The two-wheel differential steering designexhibits minimal skidding of wheels when turning. Skidding wheels candamage the type of soft surface being traveled over. So, a steeringmechanism that minimizes skidding is desirable. The two-wheeldifferential steering supports turn in place. A feature that isextremely useful for the precise turns required for the purposes of thepresent invention. With two-wheel differential steering, the steeringoccurs via the same mechanism as propulsion, avoiding additionalsteering of specific components. With two-wheel differential steering,there is a separate motor for each drive wheel, obviating the need forthe complex drive linkage required when a single engine has to powermultiple wheels in an apparatus that requires the two drive wheels tosimultaneously have differential rotational rates.

The propulsion or drive module 33 uses differential steering to move thecleaning apparatus 30 precisely down a boundary line keeping thecleaning device 34 in position for cleaning the boundary line, or simplyallowing the cleaning apparatus 30 to move to a specific point on theboundary line. The cleaning apparatus 30 is initially placed in thecenter over the boundary line and oriented down the boundary line. Thepropulsion module 33 then drives the cleaning apparatus 20 straightalong the boundary line by turning both drive wheels 36 a-36 b at thesame time. The rotational rate of each of the drive wheels 36 a-36 b isdynamically controlled by the amount of drive power delivered to each ofthe drive wheels 36 a-36 b. As the cleaning apparatus 30 is moving alongthe boundary line, the line-sensing module 31 continues to captureimages that allow a determination of the displacement of the cleaningapparatus 30 from the center of the boundary line. If the cleaningapparatus 30 begins to veer to the left, for example, the propulsion ordrive module 33 then applies slightly more differential power to theleft drive wheel 36 a than to the right drive wheel 36 b, increasing therotational rate of the left drive wheel 36 a relative to the rotationalrate of the right drive wheel 36 b. Such action causes the path of thecleaning apparatus 30 to curve slightly to the right, thereby correctingits course and keeping the cleaning apparatus 30 precisely on theboundary line being followed. Similar corrective action can be performedon the right drive wheel 36 b if the cleaning apparatus 30 begins toveer to the right.

As explained previously, the cleaning device 34 can be one of a numberof mechanisms for removing debris from a boundary line. The deploymentof the cleaning device 34 is under specific program control so that thecleaning device 34 cleans boundary lines as the cleaning apparatus 30passes over the boundary lines while causing minimal damage of the courtareas adjacent to the boundary lines. FIGS. 2-6 illustrate a cleaningdevice 34 in accordance with an embodiment of the present invention. Asshown, the cleaning device 34 includes a cleaning brush 61, a brushheight control wheel 62, an electric brush motor 63, a drive train 64,and a brush assembly hoist mechanism 65. The cleaning brush 61 iscylindrical in shape with its axis parallel to the court surface. Thewidth (cylindrical length) of the cleaning brush 61 is slightly widerthan a boundary line. During operation, the cleaning brush 61 rotatesand is in physical contact with a boundary line being cleaned. The brushheight control wheel 62 rolls on the boundary line and the rigidity ofthe brush assembly hoist mechanism 65 maintains the cleaning brush 61 tobe in contact with the boundary line. This allows the cleaning brush 61to clean the boundary line that is not perfectly flat, level and/orsmooth. The brush height control wheel 62 is positioned behind thecleaning brush 61 so as to minimize its interference with the brushoperation.

The brush motor 63 rotates the cleaning brush 61 via the drive train 64.When the cleaning brush 61 is performing a cleaning function, the brushmotor 63 is turned on; otherwise the brush motor 63 is turned off. Thedrive train 64 is a chain or belt whose linkage transfers the rotationof the brush motor 63 to the rotation of the cleaning brush 61. Theweight of the brush motor 63 is relatively significant; thus, itsposition can affect the maneuverability and stability of the cleaningapparatus 30. The arrangements as shown in FIGS. 2-6 allow the physicallocation of the brush motor 63 to be centered across the width of thecleaning apparatus 30. The arrangements also allow the brush motor 63 tobe positioned behind the cleaning brush 61 and towards the center of thelength of cleaning apparatus 30, enhancing the balance of the cleaningapparatus 30. In contrast to an arrangement in which the shaft of abrush motor in line with the brush cylindrical axis, the arrangement asshown allows the brush motor 63 to be positioned away from the courtsurface to any degree necessary to eliminate any ground clearance issuesfor the brush motor 63.

The brush assembly hoist mechanism 65 is an example of the means forlifting the cleaning brush 61 off the court surface. When the cleaningbrush 61 is deployed in its cleaning position, the position of the brushassembly (i.e., the cleaning brush 61, the brush motor 63 and the brushheight control wheel 62) can move up and down with respect to the drivewheels 36 so that the brush assembly can follow the undulations of thecourt line (or lack thereof) independently from undulations (or by thelack thereof) being encountered by the drive wheels 36.

In an embodiment of the present invention, the microcontroller 47 (seeFIG. 10) controls the operation of the line-sensing module 31, thenavigation and control module 32, the propulsion module 33, and thecleaning device 34. A single unified point of control allows theperformance of each of the above-mentioned modules to be affected by thestate of the rest of the system. For example, the navigation and controlmodule 32 “knows” when the cleaning apparatus 30 is about to reach theend of a boundary line (from knowing its starting point and knowing thedistance traveled). When in the vicinity of the end of the boundaryline, the navigation and control module 32 infers from a camera imagecontaining no court line that the end of the boundary line has beenreached. When the navigation and control module 32 knows the cleaningapparatus 30 to be only part of the way down a boundary line, as opposedto being at the end of a boundary line, and the line-sensing module 31reports that the current camera image contains no boundary line, thenwhat is inferred is that the cleaning apparatus 30 has failed to followthe boundary line or that the boundary line has become obscured fromview, for example. Similarly, when the navigation and control module 32“knows” that the cleaning apparatus 30 is approaching the end of theboundary line where it will have to stop and turn, then that informationcauses the control of the propulsion module 33 to decelerate thecleaning apparatus 30 appropriately such that a precise turn can bemade. Also, when the navigation and control module 31 “knows” thecleaning apparatus 30 is at the end of a boundary line (because ofpositioning information and the interpretation of the image provided bythe line-sensing module 31), then the drive motor 63 for the cleaningbrush 61 is turned off and the cleaning device 34 is raised to aposition at which the cleaning device 34 is not in contact with thecourt surface.

The tennis court 20 can be divided into two half courts, one on eachside of the net. The algorithm for cleaning boundary lines involvesworking the first side of the tennis court 20 and then crosses the netto the second side of the tennis court 20 and essentially repeating thesame work that was done in the first side of the tennis court 20 (see,e.g., FIGS. 13-15). For the cleaning apparatus 30 to clean a first halfof the tennis court 20, the handle 39 can be used to manually positionthe cleaning apparatus 30 on the single's sideline 21 a at the netheading towards the baseline 23 a as shown in FIG. 1. The rest of theoperations are performed automatically by the cleaning apparatus 30. Theapparatus 30, for example, can clean along the single's sideline 21 afrom the net towards the baseline 23 a and stop at the intersection ofthe sideline 21 a and the baseline 23 a. The apparatus rotates right 90degrees to head towards the double's sideline 22 a, cleans along thebaseline 22 a, and stops at the double's sideline 22 a. The apparatus 30then rotates right 90 degrees to head towards the net. It cleans thedouble's sideline 22 a and stops at the net. The apparatus 30 thenrotates 180 degrees towards the baseline 23 a, follows the double'ssideline 22 a from the net, and stops at the baseline 23 a. Theapparatus again rotates left 90 degrees to head towards the single'ssideline 21 b, cleans the baseline 23 a from the double's sideline 22 a,and stops at the center mark of baseline 23 a. The apparatus rotatesleft 90 degrees to head towards the net, cleans the center mark 26 afrom the baseline 23 a to the end of the line, backs up to theintersection of the center mark and the baseline 23 a, and rotates right90 degrees to head towards the double's sideline 22 b. The apparatus 30cleans the baseline 23 a from the center mark to the double's sideline22 b and stops at the sideline 22 b. The apparatus rotates 180 degreesto head across the baseline 23 a, follows the baseline 23 a from thedouble's sideline 22 b to the single's sideline 21 b, and stops at thesingle's sideline 21 b. The apparatus 30 once again rotates 90 degreesto the right to head along the single's sideline 21 b, cleans thesingle's sideline 21 b from the baseline 23 a to the service line 24 a,and stops at the service line 24 a. The apparatus then rotates 90degrees to the left to head along the service line 24 a.

The apparatus 30 cleans the service line 24 a from the single's sideline21 b to the single's sideline 21 a and stops at the singles sideline 21a. It rotates 90 degrees to the right to head along the single'ssideline 21 a toward the net, cleans the single's sideline 21 a from theservice line to the net and stops, rotates 180 degrees to head away fromthe net towards the baseline, and follows the single's sideline 21 a tothe service line and stops. The apparatus 30 then rotates 90 degrees tothe left to head across the service line, follows the service line tothe center line and stops, rotates 90 degrees to the left to head towardthe net, and cleans the center line from the service line to the net andstops. It then rotates 180 degrees to head away from the net toward theservice line, follows the center line to the service line and stops,rotates 90 degrees to the left to head along the service line to thesingle's sideline 21 b, and follows the service line to the single'ssideline 21 b and stops. The apparatus 30 once again rotates 90 degreesto the left to head along the single's sideline 21 b toward the net,cleans the single's sideline 21 b from the service line to the net andstops, rotates 180 degrees to head away from the net toward the baseline23 a, and follows the single's sideline 21 b from the net to thebaseline 23 a and stops.

The apparatus 30 rotates 90 degrees to the left to head across thebaseline 23 a towards the double's sideline 22 b, follows the baselineto the double's sideline 22 b and stops, rotates 90 degrees to the leftto head along the double's sideline 22 b toward the net, cleans thedouble's sideline 22 b from the baseline 23 a to the net and stops. Thelines on the first half court are done.

The apparatus now rotates 90 degrees to the right to head parallel tothe net outside the court boundaries, moves straight ahead a distancethat is just past the net post and stops, rotates 90 degrees to the leftto head in a direction parallel to the court sidelines, moves straight adistance that is just past the net post and stops. The apparatusposition is now on the second half court. The apparatus 30 rotates 90degrees to the left to head parallel to the net toward the center of thecourt, moves straight to the second half court left singles sideline andstops at the left singles sideline. The apparatus 30 rotates 90 degreesto the right to head along the single's sideline 21 a towards thebaseline.

For example, there are at least two methods for moving the cleaningapparatus 30 from one side of the net to the other. FIG. 13 depictspoints P1, P2, P3 and P4 on the tennis court 20 at which the cleaningapparatus 30 makes a turn to move around a net post. The points P1-P4are defined for illustration purpose only and have no physicalmanifestation on the tennis court 20. Point P1 is the end position ofthe cleaning apparatus 30 after cleaning a first side of the tenniscourt 20. The cleaning apparatus 30 then moves to the second side of thetennis court 20, as follows.

The apparatus 30 rotates to head towards point P2, moves from point P1to point P2, rotates to head towards point P3, and moves from point P2to point P3. The apparatus then rotates to head towards point P4, movesfrom P3 to point P4, and rotates to head away from the net and towardsthe baseline 23 b.

As the cleaning apparatus 30 approaches point P4, the cleaning apparatus30 can enable the cleaning brush 34 to expose the single's sideline 21 bat point P4 and therefore be able to visually identify when its pathintersects the single's sideline 21 b. For all of the other parts of themaneuver, the cleaning brush 34 can be turned off. Except for the visualdetermination of when point P4 is reached, all the movement andnavigation for this maneuver around the net can be controlled byodometric techniques.

Another method requires a modification to the tennis court 20 by addingthree tracking guidelines 91-93 around a net post outside the boundarylines of the tennis court 20 as shown in FIG. 14. The trackingguidelines 91-93 are made of the same material as the boundary lines andare held in place in the same manner as the boundary lines. The purposeof the tracking guidelines 91-93 is to serve as a guideline for thecleaning apparatus 30 to follow from one side of the net to the other.The tracking guidelines 91-93 are at defined positions and are ofdefined length. The steps for the cleaning apparatus 30 to go around thenet in this other method are the same as in the first method described,except that tracking guidelines 91-93 are used to guide the cleaningapparatus 30 along. As the cleaning apparatus 30 is traveling from P3and approaches the double's sideline 22 b, the cleaning brush 61 isturned off and the guideline tracking mechanism is disabled, andodometric techniques are used to navigate the cleaning apparatus 30through the rest of the way to point P4.

With the first method described, precision errors accumulate from pointP1 all the way to point P4 so that the total precision error when pointP4 is reached may be significant, which can limit the ability of thecleaning apparatus 30 to locate point P4. With the second methoddescribed, there is no accumulation of precision error so the positionerror at point P4 is only a precision error that is incurred in movingfrom just before the double's sideline 22 b to point P4, which should bea relatively insignificant amount of error. The second method describedrequires some modification to the tennis court 20, albeit outside theboundaries of play, but the first method described works on anyregulation tennis court without any modification at all.

FIG. 15 is a flowchart illustrating a method for cleaning boundary lineson a playing surface of a tennis court, in accordance with an embodimentof the present invention. Starting at block 100, a user places thecleaning apparatus 30 facing away from the net on the single's sideline21 a of the tennis court 20 to be cleaned, as shown in block 101. Thecleaning apparatus 20 follows a preprogrammed path on the boundary lineson the first half of the tennis court 20, as depicted in block 102. Thecleaning apparatus 30 completes preprogrammed path for one side of thecourt, as shown in block 103. The cleaning apparatus 30 then follows apreprogrammed path from the double's sideline 22 b around the net postto single's sideline on the opposite side of the net, as depicted inblock 104. The cleaning apparatus 30 follows a preprogrammed path on theboundary lines on the second half of the tennis court 20, verifying thepath with the on-board line-sensing module, as shown in block 105. Whencleaning is complete, the cleaning apparatus stops as shown in block106.

FIG. 16 is a flowchart illustrating the operations of the cleaningapparatus 30 for cleaning boundary lines on a playing surface of atennis court, in accordance with an embodiment of the present invention.Starting with block 170, an array of emitters illuminates the court areaon which an optical sensing device is trained, as shown in block 171.The lens focuses image on the sensor and the sensor sends information toa microcontroller, as show in block 172. A determination is made as towhether or not a line is visible, as shown in block 173. If the line isvisible, the microcontroller compares information received from sensorwith the desired line position, as depicted in block 174. Anotherdetermination is made as to whether or not the line is in a correctposition, as shown in block 175. If the line is not in the correctposition, the position of the cleaning apparatus is adjusted relative tothe line, as depicted in block 176. Otherwise, if the line is in thecorrect position, the microcontroller compares the information receivedfrom the sensor with the preprogrammed information, as shown in block177.

Next, a determination is made as to whether or not the cleaningapparatus is in the correct position, as shown in block 178. If thecleaning apparatus is not in the correct position, the position of thecleaning apparatus is adjusted relative to the preprogrammedinformation, as depicted in block 179. Another determination is made asto whether or not the preprogrammed cleaning circuit has been completed,as shown in block 180. If the preprogrammed cleaning circuit has notbeen completed, the process returns to block 171. Otherwise, the processexits at block 181.

FIG. 12 is a flowchart illustrating the operation of the cleaningapparatus 30 for cleaning boundary lines on a playing surface of atennis court, in accordance with an embodiment of the present invention.Starting with block 110, a microcontroller can get a preprogrammedlength of a line to be cleaned and type of terminating landmark, asshown in block 111. The cleaning device 34 can then be activated, asshown in block 112, When the cleaning device 34 is active, a deadreckoned position can be updated, as shown in block 113, and a nextincremental translation can be calculated, as shown in block 114. Themicrocontroller can get a next image of the line, as shown in block 115,to evaluate a lateral position of the cleaning apparatus 30 based on theimage, as shown in block 116. Power can be adjusted to the drive wheels36, as shown in block 117. Next, a determination is made as to whetheror not the cleaning apparatus 30 is close to the terminating landmark,as shown in block 118. If not, the process return to block 113,otherwise a determination is made whether the terminating landmark isvisible, as shown in block 119. If not visible, the process returns toblock 113, otherwise the cleaning device 34, is deactivated, as shown inblock 120, and the cleaning apparatus 30 is rotated at the landmark, asshown in block 121. Next, a determination is made whether all lines ofthe tennis court are cleaned, as shown in block 108. If not complete,the process returns to block 111, otherwise, the process exits at block109.

As illustrated in FIGS. 1-16, and as described above, the presentinvention also includes various methods of cleaning at least one line ofa surface. A method for cleaning boundary lines on a game playingsurface, for example, includes positioning a cleaning device on or neara game playing surface, directing a cleaning device to move alongboundary lines on a game playing surface responsive to a set ofprogrammed directions and cleaning the boundary lines when the cleaningdevice is moving along the boundary lines. The method can also includethe directing step having a step of determining a current position ofthe cleaning device by using a known initial position and an orientationof the cleaning device on the game playing surface and can use wheeldimensions and rotation data and a predetermined length of each boundaryline. The game playing surface can advantageously be a surface of atennis court, and more advantageously a clay surface of a tennis court,and the method can further include adding a plurality of trackingguidelines situated around a net post of the game playing surface forguiding the cleaning device to move around the net post. The method canstill further include sensing a location of a boundary line of a tenniscourt.

Another method for cleaning boundary lines on a game playing surface caninclude directing a cleaning device to move along boundary lines on agame playing surface responsive to a set of programmed directions andselectively positioning a cleaning tool on a boundary line to clean theboundary line as the cleaning device is moving over the boundary line.The method can also include the directing step having a step ofdetermining a current position of the cleaning device by using a knowninitial position and an orientation of the cleaning device on the gameplaying surface. The method can also include determining step furtherusing wheel dimensions and rotation data and a predetermined length ofeach boundary line. The game playing surface preferably is a surface ofa tennis court, and the method further can include adding a plurality oftracking guidelines situated around a net post of the game playingsurface for guiding the cleaning device to move around the net post. Themethod can also include sensing a location of a boundary line of atennis court.

Yet another method for cleaning boundary lines on a game playingsurface, which includes a first playing surface and a second playingsurface separated from each other by a net connected between a pluralityof posts, can include directing a cleaning device to move along boundarylines on the first playing surface responsive to a set of programmeddirections, cleaning the boundary lines on the first playing surface asthe cleaning device is moving over the boundary lines on the firstplaying surface, directing the cleaning device to move around one of thenet posts to position the cleaning device on the second playing surface,and cleaning the boundary lines on the second playing surface as thecleaning device is moving over the boundary lines on the second playingsurface. The directing step can include a step of determining a currentposition of the cleaning device by using a known initial position and anorientation of the cleaning device on the game playing surface. Thedetermining step can further use wheel dimensions and rotation data anda predetermined length of each boundary line. The game playing surfaceis preferably a surface of a tennis court, and the method can furtherinclude adding a plurality of tracking guidelines situated around a netpost of the game playing surface for guiding the cleaning device to movearound the net post. The method can further include sensing a locationof or presence of a boundary line of the game playing surface.

The present invention, as described and illustrated, also includessoftware or a computer program product residing on a computer usablemedium for directing a cleaning device to clean at least one line on asurface. As described herein and understood by those skilled in the art,the code means is preferably software or computer program code orlanguage as understood by those skilled in the art. A computer programproduct program code means for directing a cleaning device to move alongat least one line of a surface and program code means for cleaning theat least one line on the surface when the cleaning device is movingalong the at least one line. The program code means for directing canfurther include program code means for determining a current position ofthe cleaning device by using a known initial position and an orientationof the cleaning device on the surface. The program code means fordetermining further uses wheel dimensions and rotation data and apredetermined length of each line. The surface can advantageously be asurface of a tennis court.

Another computer program product for cleaning boundary lines on a gameplaying surface according to the present invention can include programcode means for directing a cleaning device to move along boundary lineson a game playing surface responsive to a set of programmed directionsand program code means for selectively positioning a cleaning tool on aboundary line to clean the boundary line as the cleaning device ismoving over the boundary line. The program code means for directing stepcan further include program code means for determining a currentposition of the cleaning device by using a known initial position and anorientation of the cleaning device on the game playing surface. Theprogram code means for determining can further use wheel dimensions androtation data and a predetermined length of each boundary line. The gameplaying surface can advantageously be a surface of a tennis court.

Still another computer program product for cleaning boundary lines on agame playing surface, which the game playing surface includes a firstplaying surface and a second playing surface separated from each otherby a net connected between a plurality of posts, can include programcode means for directing a cleaning device to move along boundary lineson the first playing surface responsive to a set of programmeddirections, program code means for cleaning the boundary lines on thefirst playing surface as the cleaning device is moving over the boundarylines on the first playing surface, program code means for directing thecleaning device to move around one of the net posts to position thecleaning device on the second playing surface, and program code meansfor cleaning the boundary lines on the second playing surface as thecleaning device is moving over the boundary lines on the second playingsurface. The program code means for directing can further includeprogram code means for determining a current position of the cleaningdevice by using a known initial position and an orientation of thecleaning device on the game playing surface. The program code means fordetermining also can further use wheel dimensions and rotation data anda predetermined length of each boundary line as understood by thoseskilled in the art. The game playing surface advantageously can be asurface of a tennis court as illustrated and described.

As has been described, the present invention provides an apparatus forcleaning boundary lines on a playing surface of a tennis court. It isalso important to note that although the present invention has beendescribed in the context of a fully functional computer system, thoseskilled in the art will appreciate that the mechanisms of the presentinvention are capable of being distributed as a program product in avariety of forms, and that the present invention applies equallyregardless of the particular type of signal bearing media utilized toactually carry out the distribution. Examples of signal bearing mediainclude, without limitation, recordable type media such as floppy disks,CD ROMs, various programmable and re-writable ROMs, and transmissiontype media such as analog or digital communications links.

Although the invention has been particularly shown and described withreference to illustrated preferred embodiments, it will be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention.

1. An apparatus for cleaning lines on a game playing surface, theapparatus comprising: a chassis; sensing means connected to the chassisfor sensing a location of a visible line that needs to be cleanedassociated with a game playing surface; driving means connected to thechassis for driving the chassis in a selected direction of travel;controlling means connected to the chassis, in communication with thedriving means, and responsive to the sensing means for controlling thedriving means to thereby direct the chassis to be driven along the linethat needs to be cleaned in the selected direction of travel; and acleaning device connected to the chassis upstream from the sensing meansas the cleaning device is being driven along the direction of travel toclean the line prior to the line being sensed by the sensing means whenthe chassis is being driven along the line; and a handle to facilitatehandling of the apparatus by a user.
 2. An apparatus as defined in claim1, wherein the sensing means includes a sensing device positioned at anelevation higher than the game playing surface and oriented to capturean image in a direction transverse to the game playing surface.
 3. Anapparatus as defined in claim 2, wherein the sensing device comprises anoptical sensing device, wherein the optical sensing device includes atleast one sensor and at least one lens, and wherein the at least onesensor includes a plurality of sensor elements positioned to capture aplurality of pixels of the image received through the lens.
 4. Anapparatus as defined in claim 2, wherein the sensing means includes anarray of illuminators positioned to illuminate the game playing surfacefor the optical sensing device.
 5. An apparatus as defined in claim 1,wherein the driving means comprises at least two drive wheels and adifferential drive connected to each of the at least two drive wheelsand positioned to independently drive each of the at least two drivewheels so that a position of the chassis when being driven along theline is compensated to enhance orientation of the chassis along theline.
 6. An apparatus as defined in claim 1, wherein the cleaning deviceincludes a frame connected to the chassis, a cleaning tool connected tothe frame, and a height control wheel connected to the frame to controlthe positional distance of the cleaning tool from the game playingsurface.
 7. An apparatus as defined in claim 6, wherein the cleaningdevice further includes a tool drive motor connected to the frame andresponsive to the controlling means to selectively drive the cleaningtool, and wherein the cleaning device further includes a tool liftassembly connected to the frame and to the cleaning tool to selectivelyraise the cleaning tool from and lower the cleaning tool to the linebeing cleaned.
 8. An apparatus as defined in claim 1, wherein thecontrolling means includes a memory having at least one of the followingpredetermined parameters stored therein: a set of predetermined lineparameters, a set of drive parameters, and a set of game playing surfaceparameters, wherein the controlling means reduces a drive speed of thedriving means to slow down the chassis responsive to the set ofpredetermined parameters when the chassis approaches an end of the linebeing cleaned, and wherein the game playing surface comprises a surfaceof a tennis court.
 9. An apparatus as defined in claim 8, wherein thepredetermined parameters further include a known initial position of thechassis and operational parameters of the cleaning device, wherein theset of predetermined drive parameters includes wheel dimension androtation data, and wherein the set of predetermined line parametersincludes a predetermined length of each boundary line of the tenniscourt.
 10. A cleaning apparatus for cleaning visible boundary lines on agame playing surface, the cleaning apparatus comprising: a cleaningdevice; a drive positioned to drive the cleaning device along at leastone boundary line of a game playing surface; a controller incommunication with the drive and the cleaning device to selectivelycontrol the driving of the cleaning device to clean the at least oneboundary line on the game playing surface when the drive is driving thecleaning device along the at least one boundary line; and a handle tofacilitate handling of the apparatus by a user.
 11. A cleaning apparatusas defined in claim 10, wherein the controller includes means fordirecting the cleaning device to move along boundary lines on the gameplaying surface responsive to a set of programmed directions to cleanthe boundary lines without cleaning substantial portions of the gameplaying surface.
 12. A cleaning apparatus as defined in claim 10,further comprising a sensing device positioned to sense a location ofthe boundary lines associated with the game playing surface that need tobe cleaned.
 13. A cleaning apparatus as defined in claim 10, wherein thedrive comprises at least two drive wheels and a differential driveconnected to each of the at least two drive wheels and positioned toindependently drive each of the at least two drive wheels so that theposition of the cleaning device when being driven along the line iscompensated to enhance orientation of the cleaning device along theline.
 14. A cleaning apparatus as defined in claim 10, wherein thecleaning device includes a frame, a cleaning tool connected to theframe, and a height control wheel connected to the frame to control thepositional distance of the cleaning tool from the game playing surface.15. A cleaning apparatus as defined in claim 10, wherein the controllerincludes a memory having at least one of the following predeterminedparameters stored therein: a set of predetermined line parameters, a setof drive parameters, and a set of game playing surface parameters,wherein the controller reduces a drive speed of the driving means toslow down the chassis responsive to the set of predetermined parameterswhen the chassis approaches an end of the line being cleaned, andwherein the game playing surface comprises a surface of a tennis court.16. A method for cleaning boundary lines on a game playing surface, themethod comprising: positioning a cleaning device on or near a gameplaying surface; directing a cleaning device to move along boundarylines on a game playing surface responsive to a set of programmeddirections; and cleaning the boundary lines without cleaning substantialportions of the game playing surface when the cleaning device is movingalong the boundary lines.
 17. A method as defined in claim 16, whereinthe directing step further includes a step of determining a currentposition of the cleaning device by using a known initial position and anorientation of the cleaning device on the game playing surface.
 18. Amethod as defined in claim 17, wherein the determining step further useswheel dimensions and rotation data and a predetermined length of eachboundary line.
 19. A method as defined in claim 16, wherein the gameplaying surface comprises a surface of a tennis court, and the methodfurther comprises adding a plurality of tracking guidelines situatedaround a net post of the game playing surface for guiding the cleaningdevice to move around the net post.
 20. A method as defined in claim 16,further comprising sensing a location of a boundary line of a tenniscourt.